1. Field of the Invention
The invention relates generally to a method for increasing the carcass yield of poultry and, more specifically, to the use of the enzyme .alpha.-galactosidase in combination with other enzymes as a feed supplement to increase the yield of the carcass and decrease fat deposition in broiler chickens fed a commercial corn/soybean meal diet.
2. Background of the Prior Art
Many grains such as wheat and barley that are typically used as feed ingredients for broiler feed contain up to 10% of a fiber fraction consisting of non-starch carbohydrates. Chickens, like other animals, are not able to digest these non-starch carbohydrates since they lack the digestive enzymes in their digestive systems. Use of exogenously supplied enzymes in wheat and barley based diets is common practice and is recognized to increase feed conversion, and frequently also body weight, as it allows the animal to utilize the otherwise non-digestible fiber portion of the diet. Enzymes used to improve the digestibility of wheat and barley are cellulases, pectinases, .alpha.-amylases and arabinoxylanases for wheat and .beta.-glucanases for barley.
The soybean meal component of a corn/soybean meal diet, and to a lesser extent the corn fraction of such a diet, contains typically non-starch polysaccharides such as galactosides which also cannot be digested by the chicken. Chickens lack the enzyme .alpha.-galactosidase, which would allow the animal to break down these non-starch polysaccharides into sugar molecules which then can be used by the animal. However, the chicken small intestinal tract houses a microbial flora that is reported to take up and utilize the galactoside fraction of soybean meal, competing not only for the energy content with the animal, but also causing secondary problems such as flatus and diarrhea.
Efforts have been made by others to produce an enzyme which will liberate nutrients from the non-digestible components of corn/soybean base diets. Results from these efficacy trials have been inconsistent. Accordingly, research on the use of enzymes such as cellulases, glucanases, xylanases, mannanases and also .alpha.-galactosidase has led to the conclusion that these enzymes improve feed conversion as well as increase body weights, but have minimal effect on increasing white meat, increasing carcass weight, or decreasing fat deposition.